Various types of imaging apparatus are known in the art. The term xe2x80x9cimaging apparatusxe2x80x9d generally encompasses any type of device that is capable of producing an image by depositing an imaging substance on an image carrier, or imaging media. Such imaging media is typically in the form of paper sheets. Imaging substance is typically in the form of liquid ink or powdered toner.
Some types of imaging apparatus include subsystems known as xe2x80x9cfusersxe2x80x9d or xe2x80x9cfusing apparatus.xe2x80x9d These fusers are employed to fix, or fuse, the imaging substance to the imaging media. For example, one type of imaging process which is presently popular is that known by the name, xe2x80x9celectrophotographic imaging process,xe2x80x9d among other names.
Imaging apparatus that employ the electrophotographic imaging process are commonly known by the name xe2x80x9claser printerxe2x80x9d because such apparatus typically employ at least one laser for operation. However, not all electrophotographic imaging apparatus employ lasers. Some such apparatus employ light-emitting diodes in place of the laser, for example.
In any case, nearly all electrophotographic imaging apparatus incorporate a fusing apparatus of some type. Usually, the fusing process involves applying heat energy and/or pressure to a sheet of imaging media which has a toner image supported thereon. The typical fusing apparatus is in the form of a pair of rollers or the like that form a nip point through which the imaging media is passed.
At least one of the rollers is typically heated. As the imaging media passes between the rollers, the toner is heated and changes from a powdered state to a plastic state. Furthermore, pressure is typically applied to the imaging media by the rollers. Upon cooling of the toner after passing through the fusing apparatus, the toner solidifies, and in the process becomes substantially bonded to the imaging media.
Many conventional fusing apparatus employ a ceramic heating element that, while providing satisfactory operation, is relatively fragile and prone to cracking.
What is needed then, is a fusing apparatus, as well as an imaging apparatus employing such a fusing apparatus, that achieve the benefits to be derived from similar prior art apparatus and methods, but which avoid the shortcomings and detriments individually associated therewith.
In accordance with the present invention, a fusing apparatus can include a circulatable contact element. The contact element has an outer surface and an inner surface. The fusing apparatus can also include a thermal insulator that is located substantially proximate the inner surface of the contact element. The thermal insulator is configured to resist the flow therethrough of thermal energy such as heat. The fusing apparatus can also include heating device operatively disposed between the thermal insulator and the inner surface of the contact element. The heating device is configured to produce thermal energy, or heat. The configuration of the thermal insulator and its location relative to the heating device and the contact element can serve to direct the flow of heat energy produced by the heater in conjunction with fusing images.